Method for combined preheating and cooling of a coolant

ABSTRACT

A method for cooling a coolant for waste heat cooling of an internal combustion engine is described for an agricultural working vehicle. The method includes providing a heat exchanger through which coolant flows and an air delivery means generates an air flow through the heat exchanger.

RELATED APPLICATIONS

This application claims the benefit of German Application Ser. No.102014220692.8, filed Oct. 13, 2014, the disclosure of which is herebyexpressly incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to a method for cooling a coolant forwaste heat cooling of an internal combustion engine in an agriculturalworking vehicle, wherein a heat exchanger through which coolant flowsand an air delivery means to generate an air flow through the heatexchanger are provided.

BACKGROUND OF THE DISCLOSURE

Fluid-based cooling systems for waste heat cooling of an internalcombustion engine are normally designed such that the cooling circuit isdivided via a coolant thermostat into a secondary cooling circuit, alsocalled the bypass circuit, and a main cooling circuit. In principle,during the warm-up phase, the coolant thermostat is in a position inwhich the flow of coolant in the main cooling circuit through the heatexchanger, also called the engine radiator, is blocked and a coolantflow through a coolant line bypassing the heat exchanger is opened. Theassociated reduction in circulated coolant leads to a faster passagethrough the warm-up phase, and the operating temperature of the internalcombustion engine is reached earlier.

In the region of the so-called “switching temperature” of the coolantthermostat, the bypass coolant line is closed to the extent that theflow through the heat exchanger is opened. Also, coolant not yet heatedis thus included in the coolant circuit and must be heated to a highertemperature. This leads to a brief fall in the temperature of thecoolant circuit. Furthermore, the warm-up phase always lasts for aspecific duration, whereas the temperature in the engine bay in whichthe internal combustion engine is placed exceeds the ambient temperaturerelatively soon after the cold start.

SUMMARY

This disclosure provides a cooling system such that a further shortenedwarm-up phase of the internal combustion engine may be achieved.

In one embodiment, a method is provided for combined preheating andcooling of a coolant for waste heat cooling of an internal combustionengine in an agricultural working vehicle, wherein a heat exchangerthrough which coolant flows and air delivery means to generate an airflow through the heat exchanger are provided, and the air delivery meansis configured to generate the air flow in a direction towards theinternal combustion engine or in a direction away from the internalcombustion engine as required, wherein the air delivery means is set togenerate an air flow in the direction away from the internal combustionengine as long as a temperature value, which is characteristic of atemperature state of the internal combustion engine, lies below athreshold value, and the air delivery means is set reversed when thestatus value is exceeded.

In one non-limiting example, the method is advantageously able toexploit the temperature difference which can occur after a cold start ofthe internal combustion engine, during the warm-up phase between theambient temperature and the engine bay temperature. Often, at the momentof cold start, the coolant in the heat exchanger is at the level of theambient temperature. During the warm-up phase a temperature differenceexists between the coolant in the heat exchanger and the engine bay. Themethod according to one example achieves that, on reaching the switchingtemperature of the coolant thermostat, i.e. on opening of the flowthrough the heat exchanger or the main cooling circuit, there is no orat least only a reduced brief temperature fall in the coolant circuit.Furthermore, the method shortens the duration of the warm-up phase sincean additional heat input into the coolant circuit takes place during thewarm-up phase. This heat input can come from a heat source, for examplethe exhaust manifold, the emitted heat of which is not normally used forany other purpose. To this extent, the efficiency of the internalcombustion engine increases during the warm-up phase.

In one non-exclusive example, the threshold value is at the level of theoperating temperature of the internal combustion engine. This ensuresthat as far as possible, the entire warm-up phase is used to guide air,which has already been heated in the engine bay, through the heatexchanger. In another non-exclusive example, the air delivery means is afan with electric or hydraulic drive.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned aspects of the present disclosure and the manner ofobtaining them will become more apparent and the disclosure itself willbe better understood by reference to the following description of theembodiments of the disclosure, taken in conjunction with theaccompanying drawings, wherein:

FIG. 1 is an agricultural working vehicle with a cooling systemcontrolled according to one embodiment; and

FIG. 2 is an agricultural working vehicle with a cooling systemcontrolled according to another embodiment.

Corresponding reference numerals are used to indicate correspondingparts throughout the several views.

DETAILED DESCRIPTION

FIG. 1 shows an agricultural working vehicle 12, depicted purelydiagrammatically in parts, with a cooling system 10 arranged in afrontal area, for waste heat cooling of an internal combustion engine 20placed in the engine bay 18. The agricultural working vehicle 12furthermore may have a cab 14, a front axle 16 and a rear axle 22 drivenby the internal combustion engine 20. A frame 24 serves a carrierelement for the individual components of the working vehicle 12.

To dissipate the heat developed during operation of the internalcombustion engine 20, the cooling system 10 may have a heat exchanger 28through which coolant flows and over which air flows, and the airdelivery means 32 generating the air flow, in the form of a fan. Boththe heat exchanger 28 and the fan 32 may be arranged at the front of theinternal combustion engine 20 in the travel direction of the workingmachine 12. The fan 32 may also be arranged between the internalcombustion engine 20 and the heat exchanger 32.

In the illustrated embodiment shown in FIG. 1 and described herein, thefan 32 may be driven about a rotation axis D by a hydraulic motor 30,which in turn may be supplied by a hydraulic pump 26 driven by theinternal combustion engine 20. According to this embodiment, it isproposed that the fan 32 can be driven by the hydraulic motor 30 both inthe one rotation direction and in the opposite rotation direction asrequired. In another embodiment, the fan 32 may similarly be driven byan electric motor.

In FIG. 1, the air flow generated by the fan 32 is depicted by arrowswhich represent a flow direction of the air flow from the environmentthrough the heat exchanger 28 and into the engine bay 18. The fan 32 isthus set and driven in the rotation direction in which, at least whenthe internal combustion engine 20 is at operating temperature, an airflow is generated which acts as a cooling air flow from the environmentinto the engine bay 18.

In FIG. 2, the fan 32 is set and driven in the opposite rotationdirection, so that an air flow is generated out of the engine bay 18,through the heat exchanger 28 and into the environment. In this rotationdirection, here called the opposite direction, the fan 32 is set torotate in the opposite direction immediately after the cold start andduring the subsequent warm-up phase of the internal combustion engine20. The term “cold start” in the context of this application means astate in which a temperature level of the internal combustion engine 20,which is represented for example by the coolant temperature or theengine oil temperature, lies significantly below the operatingtemperature of the internal combustion engine 20, wherein the operatingtemperature is usually characterized by a coolant temperature betweenabout 80° C. and 100° C. or an engine oil temperature between about 90°C. and 110° C.

To perform the method according to one nonexclusive aspect of thisdisclosure, first a coolant temperature sensor, an engine oiltemperature sensor and an external temperature sensor present on theagricultural working vehicle 12 detect whether a cold start stateexists. If a cold start state exists, after the cold start of theinternal combustion engine 20, the fan 32 is set and driven in theopposite direction of rotation so that an air flow is generated from theengine bay 18, through the heat exchanger 28 and into the environment.Since the exhaust manifold quickly becomes hot after a cold start of theinternal combustion engine 20, this heats the engine bay 18 rapidlyrelative to the ambient temperature. This increased temperature is usedto heat the coolant present in the heat exchanger 28 before the coolantthermostat has reached its switching temperature and opened the flowthrough the main cooling circuit. When the internal combustion engine 20has reached its operating temperature, the rotation direction of the fanis reversed, and it is set and driven in the rotation direction in whichan air flow is generated which acts as a cooling air flow out of theenvironment into the engine bay 18.

In other embodiments, a variable pitch blade fan with reversingcapability may be used instead of a fixed blade fan. With a variablepitch blade fan, the direction of air flow can be reversed withoutreversing the direction of rotation of the motor.

While embodiments incorporating the principles of the present disclosurehave been described hereinabove, the present disclosure is not limitedto the described embodiments. Instead, this application is intended tocover any variations, uses, or adaptations of the disclosure using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this disclosure pertains and which fallwithin the limits of the appended claims.

1. A method for combined preheating and cooling of a coolant for waste heat cooling of an internal combustion engine in an agricultural working vehicle, the method comprising: providing a heat exchanger through which coolant flows and an air delivery means to generate an air flow through the heat exchanger; generating air flow via the air delivery means in a direction towards or away from the internal combustion engine as required; detecting a temperature of the internal combustion engine; producing air flow in the direction away from the internal combustion engine when a temperature value of the internal combustion engine is below a threshold value; and reversing the air delivery means when the temperature value exceeds the threshold value.
 2. The method of claim 1, wherein the threshold value is established at a level of an operating temperature of the internal combustion engine.
 3. The method of claim 1, wherein the air delivery means comprises a fan with an electric or hydraulic drive.
 4. The method of claim 3, wherein the fan has fixed blades.
 5. The method of claim 3, wherein the fan has variable pitch blades. 